core/smartcontracts/voting: missing tally returns 0-val
core/smartcontracts/voting: missing tally returns 0-val

The tally call sums up the amount of voting tokens in various states in
the blockchain. It should not return a 404 for an asset that has not
been distributed, and should instead just return the empty value.

Closes chain/chainprv#954.
Reviewers: 3b4aa14b5d886b2421455653a1073134c936a0c5@kr

chain/chain,chain/chain,chain/chain,chain/chain,chain/chain,chain/chain